Scope 1, 2 and 3 emissions, explained
Scope 1, 2 and 3 emissions are the three buckets the GHG Protocol uses to divide a company's greenhouse gas footprint. The split exists so that no emission is counted twice when several companies in a supply chain all report — and so that anyone reading an inventory can see at a glance how much of it the company directly controls.
The three scopes in one paragraph
Scope 1 is what you burn: fuel in your boilers, furnaces and vehicles, plus process emissions from the chemistry of production itself. Scope 2 is the energy you buy: grid electricity, district heating and cooling. Scope 3 is everything else in your value chain, upstream and downstream, across fifteen categories.
The boundary between them is ownership and control, not distance. Electricity generated in your own plant is Scope 1. The identical electricity bought from the grid is Scope 2.
Why Scope 1, 2 and 3 emissions are split this way
Because supply chains overlap. Your Scope 1 is your customer's Scope 3. If everyone simply reported "their emissions", the same tonne would be counted at every step from mine to shelf, and no total would mean anything.
The split also makes an inventory readable. A company with large Scope 1 emissions owns its problem directly. A company whose footprint is almost entirely Scope 3 is mostly reporting on decisions other people made.
Which scope is actually being asked for
Nearly every real request — from a bank, a buyer or a CBAM declarant — is a request for Scope 1 and Scope 2 done properly, plus one or two Scope 3 categories that the customer names.
This matters because Scope 3 is where companies lose months. Fifteen categories, most of them estimated, none of them evidenced, and the requester usually only wanted two. Answer what was asked, state the boundary, and move on.
What a verifier checks
Not whether the number is low. Whether it can be rebuilt. That means the activity data traces to a document, the emission factor is the right one for that country and that year, the version of the factor is recorded, and the boundary is stated rather than implied.
An inventory where 89% of the footprint is backed by documents and the remaining 11% is openly marked as estimated will pass review more easily than one that looks complete and cannot be checked.
Go deeper
Individual definitions: Scope 1 emissions, Scope 2 emissions, Scope 3 emissions. For the regulation that triggers most requests, see the CBAM report guide.